Characterization of Functional Roles of Three Types of Chloride Channel in Rat Parotid Gland Acini Cells In the parotid gland acini cells as in many other secretory cells, the salt and fluid secretion is dependent on the transepithelial chloride transport. Our lab has recently discovered three different types of chloride channels in the parotid acini cells - voltage activated, volume activated, and calcium activated - requiring the characterization of functional roles of each type to understand better the physiology of saliva secretion. My specific aim of this project is as follows: 1) I will study how secretory stimulation effects the gating open probability) of each channel temporally in relationship to the intracellular calcium and membrane potential. 2) I will study spatial distribution of three types of channel to correlate their cellular location and the physiological function. 3) I will attempt to modify current models of salt and fluid secretion to build a new analytical model incorporating the three types of chloride channels, to explain clearly the phenomena of salivary secretion and also to guide and direct further study.